Hi,
>I guess the EPROM is a copy of the real FM-PAC ROM;
Not completely, AFAIK. The original FM-PAC included
a complete menu program to read/write S-RAM slots and
a music demo, if memory serves me well. It could be called
up from BASIC using '_FMPAC'. That's not included in the
Zemina version.
> What is interesting is that there is a preset resistor inside
> the cartridge which acts as a volume control. It is an enclosed
> type, which indicates fairly high quality, and the op-amp is
> an HA17558 which is also perfectly reasonable. So why did
> my Zemina MSX-MUSIC sound so distorted?
> Turns out the volume control was turned up too loud for the
> MSX computer it was plugged into.
Heheh, that's a well-known glitch of the Zemina's :-)
> Perhaps Zemina machines themselves have different
> gains on their SOUND IN lines. Anyway, once the volume
> was turned down with a screwdriver, the cartridge sounded fine.
I actually drilled (hm, using X-acto & scissors ;-)) in the cartridge
so I could reach for the resistor without opening the cartridge :-)
Still, the sound of a Zemina contains much more noise than that of
the original FM-PAC. I myself have a cartridge made by 'Digital KC',
which includes somewhat better electronics and filters and has a
separate line out, so the sound is almost crystal clear...
Eric
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